In many situations, labels must be adhesively attached to surfaces of articles which are moving in an assembly-line fashion. The labels are typically fashioned with an adhesive surface which is attached to a backing strip from which the labels are removed. The labeling of the articles is carried out by a label application device which first removes the labels from the backing strip to expose the adhesive surface and then applies the labels to the surfaces of the articles as the articles move past the label applicator.
In mail sorting situations, there are many occasions where labels must be applied to envelopes as the envelopes move along a conveying path through a mail sorting apparatus. One occasion is when the envelope must be supplied with a label on which a bar code will be applied. The bar code then is read to sort the envelope at a location downstream from the labeling station. Typically, mail handling devices have a very high rate of mail throughput which translates to a large number of envelopes moving very quickly along the conveying path of the mail handling apparatus.
In labeling devices, it is known to use a peeling bar to remove the labels from the backing strip. The backing strip carrying the label is tautly pulled across the peeling bar which causes the label to separate from the substrate. The peeled label is then retained against a surface of an applicator by suction or vacuum pressure to expose the adhesive surface. An article onto which the label is to be applied is then momentarily held in close proximity to the label holding surface. The label may be applied to the article by use of a blast of air to force the label against the article. Alternately, the holding surface is linearly advanced toward the article and the label is applied by contact between the article and the holding surface.
This attaching arrangement and method may work for many applications, particularly when the article may be momentarily held in the application location. However, in the mail handling apparatus where large numbers of envelopes or other articles are moving very quickly along the conveying path and even momentary retention is not feasible, use of these devices have significant drawbacks. For example, using a blast of air to apply the label may cause an upstream edge of the label to initially contact the envelope. Because the envelope is rapidly moving, the label will wrinkle before the other portions of the label contact the surface of the envelope.
Also, in both the air applicator and linearly moving surface, if the holding surface and envelope surface do not correspond, the problem of wrinkling may also occur. This correspondence is rare in mail handling as the envelopes may contain contents having varying thicknesses and configurations. In addition, the forces required to linearly reciprocate the mass of the moving applicator may preclude use of this type of device in a mail handling situation where the number of reciprocations is very high.
It is therefore an object of the present invention to provide a labeling system for applying labels to moving surfaces, and more particularly a labeling system for a mail handling apparatus.
It is another object of the present invention to provide a labeling system which may apply to moving surfaces, labels which are carried on a backing substrate.
It is a further object of the present invention to provide a labeling system which may apply labels to moving surfaces in a manner which reduces wrinkling.
A still further object of the present invention is to provide a labeling assembly which may apply labels to envelopes and other documents in high volume, high throughput sorting equipment.